High reactance transformer



March 28, 1950 w, o s 2,502,082

HIGH REACTANCE TRANSFORMER Original Filed Sept. 26, 1941 IN V EN TOR.M/ILLMMFOER: 7':

A T TOAWEX Patented Mar. 28, 1950 men REACT/moi: TRANSFORMER WilliamFoerste, Pelham Manor, N. Y.; Anna Kane, administratrix of said WilliamFoerste, deceased, assignor oi one-half to Eugene A. Quarrie, Scarsdale,N. Y.

Original application September 26, 1941, Serial No. 412,492. Divided andthis application July 30, 1945, Serial No. 607,748

4 Claims. (01. 323-45) The invention relates to high reactance, magneticleakage transformers suited, for example, to the operation of rectiflerssuch as the gasfllled or oxide types, variable speed motors, gasfilledlamps of the ordinary luminescent or fluorescent types, germicidal andultra-violet lamps, etc.

Regulation of the output of transformers of this nature is attempted, asa rule, by including in circuit with the primary or the secondary oi theoperatin transformer large value impedance, or variable voltage supplydevices, which increase the cost of and reduc the voltage applied by thetransformer. Such expedients result, generally, also in inefficient,unsatisfactory and unstable operation of the apparatus connected withthe transformer.

The present application is a division of my application Serial No.412,492, filed September 26, 1941 which has matured into U. S. LettersPatent No. 2,392,845, dated January 15, 1946.

' It is an object of the instant invention to provide a transformer ofhigh reactance which will develop th required high initial potential andat the same time allow for variations in the output of its secondarythrough control of its primary circuit for the operation of thehereinbefore-noted apparatus.

A further object of the invention is to provide a transformer which willbe particularly suitable for the operation of a luminescent tube atdifferent intensities of illumination.

Another object of the invention is to provide a simple and ruggedconstruction of transformer by embodying the control features as anintegral part of such transformer.

In carrying out the invention, there is associated with th usual closedmagnetic core only one primary and at least one secondary, a highreluctance variable reactor being associated with said core insingle-acting shunt magnetic relationship. This reactor is magneticallypositioned between said primary and secondary, and separated from thecore by a non-magnetic gap for shunting from said secondary a portion ofthe flux generated by the said primary. It includes a coil forcontrolling the load of said single primary, means being provided, also,whereby said reactor coil may be connected in series with the primaryor, alternatively, the latter directly to a source of electrical energy.In addition, a plurality of taps may be taken from the reactor coll,which taps may be selectively connected by the aforesaid means in serieswith the primary.

The nature of the invention, however, will best 2 be understood whendescribed in connection with the accompanying drawings, in which:

Fig. 1 is a diagrammatic view of the novel transformer with controlarrangement, and is shown connected, by way of example, to a luminescentlamp for operation thereof at different intensities of illumination.

Fig. 2 is a similar view illustrating a modification.

Referring to the drawings, more particularly Fig. 1 thereof, Itdesignates the closed core structure of the novel transformer, which maybe constructed in the usual manner of laminated iron, said coreaffording a closed magnetic circuit. A single primary winding I isprovided on the core. and derives its power from the electrical energysupply main l2 through lead i 3 and a switcharm l4. At least onesecondary winding such as the winding I5 is also provided on the core,for supplying power at a substantially constant open-circuit voltage toan adjustable load which may be of relatively low operating voltage, forexample, as in the case of loads such as are encountered in theoperation of gas-filled lamps of the ordinary luminescent type or of thefluorescent type. Thus, the said secondary winding is shown, by way ofexample, as connected directly to the electrodes is and 11, either ofthe hot or cold type, of a luminescent lamp including a transparentenvelope I8. Winding I5 is thus in inductive relationship to theprimary, being coupled as closely as possible thereto, and supplies thelamp with the requisite voltage for its proper operation.

In the operation of these lamps, it is understood that an initially highvoltage must be supplied by the secondary to effect the ionization ofthe rare gas in the envelope, this voltage dropping then to a much lowersustaining or working voltage when the lamp is in service or duringone-half cycle of operation. The novel arrangement set forth, however,affords at the same time a ballast to prevent overheating of the tubeand disintegration of the tube elements, thereby maintaining the currentdensity and the light intensity.

In accordance with the invention, an auxiliary core 20 is associated insingle-acting shunt magnetic relationship with the core, for example,extending within the main core structure as shown to afford a highleakage reactance element or magnetic shunt separated from the core by anon-magnetic gap, and serving to shunt from the secondary IS a portionof the flux generated by the said primary !I. There is provided over thesaid auxiliary core 20 a winding control tor the primary load, and thesaid winding is divided, for

example, into two coil portions 2| and 22. As shown, the winding isdivided, preferably, midway to this end by connection of the lead orintermediate tap 23 from the primary ll substantially to the mid-pointof the said winding.- Respective leads 24 and 2! connect the terminalsY23 and 21 of the windings to contact points 28 and 29, respectively.

Connection is also made from lead 23 to a contact point 30 through lead3|, all contacts being associated with the switch-arm l4 designed forengagement therewith. By this expedient, the winding on the auxiliarycore is constituted of two coils 2| and 22 either one of which may beconnected in circuit with the primary II, or the latter may be connectedwithout either of these coils in circuit by setting the switch-arm I4 onthe switch-point 30. In the latter instance, the transformer willoperate in the usual manner with core 20 introducing a certain amount ofreactance due to the normal magnetic leakage provided thereby. However,the amount of this reactance may be respectively increased or decreasedaccordingly as one or the other of the coils 2i or 22 is energized bysetting the switcharm 14 to switch-point 28 or switch-point 29,respectively-the one coil being subtractive in its effect, developing anopposing flux, and the other additive, developing a like flux, withrespect to the reactance normally introduced by the core 20.

The magnitude of the flux of the core may thus be varied and while thiswill accordingly vary the current supplied, the open-circuit voltagedelivered by the secondary i5 remains substantially constant inaccordance with the requirements of the lamp and the relationshipbetween the number of primary and secondary turns. The dimensions of thecore, more especially its length, will be according to the requirementsof the variation desired and the core may be omitted entirely in someinstances and merely the solenoid utilized. The leakage effect of thecore will then, of course, be missing and only the solenoid is effectiveto provide for leakage and in accordance with the current flowing in theprimary winding.

This particular type of control lends itself, also, to the production offlasher apparatus or light beacons and in which it is possible,moreover, to provide automatically consecutive illuminations ofdifferent intensities. For example, a thermostatic circuit-controllingdevice may be included in series in a circuit across the contact points28 and 30, and there is included in the two leads and 31 of said circuita switch 38 whereby the eii'ect of the thermostatic device 35 may beintroduced or dispensed with accordingly as the switch 38 closes thecircuit or opens the same. When the switch 38 is in the closed position,and the contact 39 of thermostatic device 35 also is in position toclose the said circuit at this contact, one of the windings on core 20is by-passed and opposes the core flux. The current supplied to thesecondary i5 and the lamp connected thereto will then be of oneintensity, switch-arm l4 having been moved first to the positionindicated in the broken lines, on switch-point 28. This connects theprimary ll directly with the supply main I2; and current flowing throughthe leads 36-'--3| will eventually cause the thermostatic device 35 tooperate to open said by-passing-cir- Quit at the contact 39 thereof.

This latter circuit is then ineflective and the current to the primary II must also iiow through a selected one of the windings on core 25, inthe present instance the winding 2|. This will afford a secondarycurrent of a different value with corresponding change in the lightintensity of the lamp.

Various combinations, of course, are possible by providing for differentconnections of the thermostatic device to other switch-points, as willbe readily understood; and in instances where the auxiliary or leakagecore contains but a single winding, a simplified arrangement becomespossible involving cutting out merely such winding alternatively withits inclusion with the primary.

Fig. 2 illustrates a modified form of the novel transformer construltionin which the main core structure includes a cross-core 40 upon which theprimary winding 4| as well as the secondary winding 42 is located. Inaddition, two auxiliary cores or high-leakage reactance elements 43, 44are provided extending midway of the transformer structure toward thecross-bore 40. Each one of these latter cores 43 and 44 is provided witha corresponding winding 45 and 46, respectively, which are arranged tobe placed alternatively in circuit with the primary winding 4|. This maybe effected by the switch-arm connected to one lead 5| of the supplymain 52, the other lead 53 being connected directly to one terminal ofthe primary winding 4|. The other terminal of said primary winding isconnected through lead 54 to a switchpoint 55, as well as to oneterminal of the winding 45 whose other terminal is connected throughlead 55 to a switch-point 51. This latter terminal of the winding 46also is connected to one terminal of the winding 45 whose other terminalis connected through lead 58 to switch-point 59.

In accordance with the position of arm 50 with respect to theswitch-points 55, 51, and 59, various currents will be supplied tosecondary winding 42 for illumination of the lamp 6|] at diiierentintensities.

' I claim: I

l. A current-regulating mean for apparatus operating at substantiallyconstant open-circuit voltage, comprising a transformer having a closedmagnetic core, only one primary winding and at least one secondarywinding; high reluctance variable reactor means in single-acting shuntmagnetic relationship with said core, magnetically positioned betweensaid primary and secondary windings and separated from the core by anonmagnetic gap for shunting from the said secondary winding a portionof the flux generated by trical energy supply.

3. The transformer of claim 1, wherein the reactor coil is provided witha. plurality of taps, and a switching means is provided for connectingthe reactor coil alternatively in series with the primary winding or thelatter in series with a selected tap of said reactor coil.

4. The transformer of claim 1, wherein a circuit is provided forshort-clrcuiting the reactor coil,

and a clrcmt-interrupting means 1; included m STATES PATENTS therein.

WILLIAM FOERSTE. Number Name Date 604,459 Duncan May 24, 1898 REFERENCESCITED 5 2,179,795 'McCurtaJn Nov. 14, 1939 The following references areof record in the 23123 Mitchell 1943 file of this patent:

